Electronic, Magnetic, and Spectroscopic Properties of Molecular Solids

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Non-technical abstractThis research addresses molecular materials, an area of emerging importance. These materials, which are carbon based and often called "organic", are beginning to complement, or even replace materials such as copper, silicon, and others that have been the mainstay of technology. Research questions and investigations involve how electrical conductivity, magnetism, and superconductivity arise and behave in molecular materials, and how to modify the materials to exploit desirable new properties. Diverse methods are employed, including high pressure, high magnetic field, and low temperature environments, in conjunction with electrical, magnetic, and spectroscopic (optical, x-ray, magnetic resonant) probes. The award mainly supports graduate students. Their work and training is interdisciplinary, and designed to prepare them to solve problems in a competitive global environment. Each student interacts with scientists outside their immediate area, including chemists (who provide many materials) and engineers (who have advanced methods of characterization and the culture of finding relevance to applications). Through interactions with National Laboratories and NSF-supported international programs, students are exposed to many different areas of materials research, often collaborating with world-class experts. Likewise, students play active mentorship roles in middle school, high school, REU, RET, senior thesis, and other training programs.Technical abstractThis award addresses the nature and interaction of spin, charge and lattice degrees of freedom in anisotropic (low-dimensional) materials generally described as organic conductors or superconductors, molecular conductors or magnets. The approach is experimental, utilizing transport, structural, spectroscopic, thermodynamic, optical, and resonant probes. Although the work is fundamental in scope, the understanding and control of electronic charge (conduction) by spin (magnetism), and vice versa, on the molecular level is an important goal in many fields of science. A main theme of the project is the comparative behavior of isostructural materials where only the localized d-electron spin at one lattice site, or more generally, in one molecular chain or plane, can be turned on or off by chemical alloying. Questions to be answered include: How do the d-electron spins and the pi-electron spins order magnetically? How do they interact? What is the role of the lattice in these interactions? Can charge and spin be controlled by external parameters? The highly interdisciplinary nature of molecular materials provides an excellent venue for wide collaborations and international experiences for young researchers in degree programs. This theme, with a broad range of topics to choose from, offers simple bench-top projects that draw young researchers at the pre-degree level to the lab to test and develop their scientific interests and skills